The Bluefin Tuna Fishery Today
A modern tuna purse seine vessel.
_Today, bluefin tuna support a worldwide $7.2 billion industry. An international fleet of thousands of long-liners catch millions of tons of tuna every year. [7]
The major consumers include Japan, the United States, Canada, Spain,
France, Italy, China, Australia, New Zealand, South Korea, Taiwan, and
New Zealand. The fish are caught using a variety of methods, including hook-and-line, harpooners, purse seine, and most important, long-line. This site through the Monterey Bay Aquarium summarizes how these methods and others work.
As a result of the importance of bluefin tuna fisheries, overfishing has caused worldwide stocks of these fish to plummet by 90% since 1976. Major factors that have led to this decimation include the highly increased power of new fishing technology to catch and kill, fishery management and enforcement that has been neglected, the huge and sometimes untrustworthy international network of fisheries, and the indifference of the consumer to the sustainability of the fish they choose to buy and eat. [8] It is difficult to determine the status of bluefin tuna stocks because catch and effort data from fisheries is unreliable at best. It has been concluded that population abundances are down and there is a heavy take of juveniles. [9]
As a result of the importance of bluefin tuna fisheries, overfishing has caused worldwide stocks of these fish to plummet by 90% since 1976. Major factors that have led to this decimation include the highly increased power of new fishing technology to catch and kill, fishery management and enforcement that has been neglected, the huge and sometimes untrustworthy international network of fisheries, and the indifference of the consumer to the sustainability of the fish they choose to buy and eat. [8] It is difficult to determine the status of bluefin tuna stocks because catch and effort data from fisheries is unreliable at best. It has been concluded that population abundances are down and there is a heavy take of juveniles. [9]
Aquaculture
_
Australia (Southern bluefin) –
Ranching - This is one of the largest farmed seafood sectors in Australia, where juveniles are caught and then raised in captivity until they are large enough for to eat. These fish are so valuable, they are watched over by armed guards and are worth approximately $2 million for 2,000 tuna. In this area, research is being done in bluefin tuna ranching that aims to increase the quality and safely of the products, improve methods for health and environmental management, and prevent the diseases common in the ranches. [10]
Complete aquaculture - A relatively new idea, complete aquaculture stems from the development of hormonal therapy by Europe and Japan in 2007. These hormones allow fishermen to breed bluefin tuna, rather than catch and raise them. The sperm and eggs of Southern bluefin tuna have successfully been collected from the spawning of captive tuna in a land-based breeding facility in southern Australia. This significant advance allows for the sustainable production of tuna, where it is possible to duplicate Australia's Southern bluefin tuna annual quota without impacting wild stocks. This also allows for the growth of the aquaculture industry in the region. [11]
Mediterranean Sea (Northern bluefin) – In this region, wild tuna are caught, fattened, and slaughtered. The fattening technique was developed by a group of Croatians, who first worked with Southern bluefin in Australia. In 1996, the first tuna ranch in the Mediterranean was established. Here, newly caught tuna are placed in coastal sea sages and fed oily fish like anchovies or sardines for months to years. When they are finally killed, the flesh of the fish contain the high fat content that Japan and other consumers look for.
This form of aquaculture has created even more problems. Ranching removes bluefin tuna from all stages of their life cycle, which prevents wild population growth. Juveniles are killed before they can spawn and large females, who have the ability to produce 40 million eggs, are likewise removed. What is more, removing bluefins from wild populations only decreases the number of fish fishermen can catch in an already very competitive market. To top it off, these ranches have made it difficult for the European Union and national governments to enforce their quotas. Because the tuna are not killed when they are caught, they do not count within a quota. [8]
Japan (Pacific bluefin) - Aquaculture in Japan began in a way that is very similar to how it is in the Mediterranean Sea today - bluefin tuna were caught from the wild and raised in pens and cages until they were large enough to slaughter and sell. Research done at a university in Japan allowed these ranches to raise bluefins using a technique that would later be used in Australia. By raising the fish in bigger pens and adjusting water temperature and diet, scientists were able to have bluefin tuna completely raised outside of the wild in 2004. [12]
Ranching - This is one of the largest farmed seafood sectors in Australia, where juveniles are caught and then raised in captivity until they are large enough for to eat. These fish are so valuable, they are watched over by armed guards and are worth approximately $2 million for 2,000 tuna. In this area, research is being done in bluefin tuna ranching that aims to increase the quality and safely of the products, improve methods for health and environmental management, and prevent the diseases common in the ranches. [10]
Complete aquaculture - A relatively new idea, complete aquaculture stems from the development of hormonal therapy by Europe and Japan in 2007. These hormones allow fishermen to breed bluefin tuna, rather than catch and raise them. The sperm and eggs of Southern bluefin tuna have successfully been collected from the spawning of captive tuna in a land-based breeding facility in southern Australia. This significant advance allows for the sustainable production of tuna, where it is possible to duplicate Australia's Southern bluefin tuna annual quota without impacting wild stocks. This also allows for the growth of the aquaculture industry in the region. [11]
Mediterranean Sea (Northern bluefin) – In this region, wild tuna are caught, fattened, and slaughtered. The fattening technique was developed by a group of Croatians, who first worked with Southern bluefin in Australia. In 1996, the first tuna ranch in the Mediterranean was established. Here, newly caught tuna are placed in coastal sea sages and fed oily fish like anchovies or sardines for months to years. When they are finally killed, the flesh of the fish contain the high fat content that Japan and other consumers look for.
This form of aquaculture has created even more problems. Ranching removes bluefin tuna from all stages of their life cycle, which prevents wild population growth. Juveniles are killed before they can spawn and large females, who have the ability to produce 40 million eggs, are likewise removed. What is more, removing bluefins from wild populations only decreases the number of fish fishermen can catch in an already very competitive market. To top it off, these ranches have made it difficult for the European Union and national governments to enforce their quotas. Because the tuna are not killed when they are caught, they do not count within a quota. [8]
Japan (Pacific bluefin) - Aquaculture in Japan began in a way that is very similar to how it is in the Mediterranean Sea today - bluefin tuna were caught from the wild and raised in pens and cages until they were large enough to slaughter and sell. Research done at a university in Japan allowed these ranches to raise bluefins using a technique that would later be used in Australia. By raising the fish in bigger pens and adjusting water temperature and diet, scientists were able to have bluefin tuna completely raised outside of the wild in 2004. [12]